Figure 3.

Overlap between expression levels of mGlu₂ in native and transfected neurons. Expression of mGlu₂ receptor in native and transfected primary hippocampal neurons was measured by immunofluorescence using a d2-labeled single domain antibody (DN1-d2) specific for the mGlu₂ receptor. (a) Schematic drawing of DN1-d2 labeling of the mGlu₂ receptor. (b) Image of a DN1-d2 labeled native neuron with endogenous expression of mGlu₂ receptor by epifluorescence microscopy. (c) Mean intensity of DN1-d2 labeling of neurons for endogenous (28 cells) or transfected (26 cells) mGlu₂ receptor expression. To compare the expression of endogenous mGlu₂ receptors with the expression levels obtained in N&B experiments, the DN1-d2 mean intensity in transfected neurons was normalized to the mean number of mGlu₂ subunits per effective volume (V_eff) in transfected neurons determined with sN&B. The standard deviations of the transfected receptor densities in the DN1-d2 labeling and the sN&B experiments were similar after normalization (320 and 310 subunits/V_eff, respectively). The endogenous mGlu₂ expression overlaps with the expression in transfected neurons in the 55–170 subunits/V_eff range (shaded area), whereas the mean expression is higher in transfected neurons (p = 0.0001 (DN1-d2) or p < 0.0001 (sN&B), one-way ANOVA, Bonferroni’s multiple comparisons test). Data are from 4 (DN1-d2) or 14 (sN&B) independent experiments.